FLINT, MI -- General Motors is investing $600 million in Flint Assembly, its oldest assembly plant, setting it up with a state-of-the-art paint facility and other upgrades that officials say will keep it on a par with production lines that are decades newer.

"You earned this -- everybody who works hard every day," GM Executive Vice President and North America President Mark Reuss told workers and plant managers Monay, Dec. 16. "These are investments in the future (that will last) for a long time."

Reuss, UAW, city, state and federal officials cheered the announcement inside the truck plant -- but no group made more noise than the dozens of employees who came to hear the news first-hand.

"It should secure all our futures so we can retire from here," said Tony Robinson, who has worked at the truck plant since 1995. "It's great news for the city and the plant."

The $600 million for Flint was part of a broader announcement of about $1.3 billion in GM investments in five plants: Flint, Detroit and Romulus; Toledo, Ohio; and Bedford, Ind.

An engine plant in Romulus will get $493 million to build a new V-6 engine and 10-speed automatic transmissions; about $121 million will go for a logistics center at a Detroit factory; $31 million will upgrade a Toledo, Ohio, plant to build more six-speed transmissions; and a casting plant in Bedford, Ind., will get $29.2 million to make transmission parts.

Although some of the spending in Flint is specific, including $124.5 million for the new 596,000-square-foot paint facility, some of the upgrades won't be discussed in detail until later, said Tom Wickham, a Flint-based spokesman for GM.

"We'll get into more detail after the first of the year, but you're going to need things like new conveyance systems and other things we're not ready to talk about" because of the new paint facility, Wickham said.

Information posted on GM's Web site says new paint shop will be just the third in North America to use an environmentally friendly wet-coat paint process.

Plant Manager Amy Farmer called the facility "the key to our long-term future."

Not only will the change in equipment mean a 90 percent reduction in sludge to landfills and require 20 percent less gas and 40 percent less electricity to operate, it will also provide what GM says will be a "first-class appearance" on the Chevrolet Silverado and GMC Sierra pickup trucks built in Flint.

"In the five years I've been here, we as a group committed that this would be a place where GM would do business for a long time," Farmer said. "Together, we made this possible."

Site work in FLint will begin January 2014 with construction starting in the second quarter of 2014, GM officials said. The facility will be completed in 2016 with the first units scheduled to be painted in October 2016.

UAW Local 598 President Ray Gorney said the paint upgrades were critical to the future of Flint Assembly, which GM built in 1947.

"We know for us to build world-class trucks and have security in our future we would have to have a new paint shop," Gorney said. GM '"never had to(worry whether) they had the people who could do this work" in Flint.

A fact sheet from GM says the new paint facility will be located on land south of Flint Assembly and will require approximately 1 million construction man hours with full production scheduled for the third quarter of 2016.

Flint Mayor Dayne Walling called the commitment from GM an "incredible investment" and said, "The best trucks in the world ... are made right here in Flint."

"We've been through a lot ... We live in an uncertain world, (and) the global economy is challenging," Walling said, but "GM and Flint's partnership has been renewed here today."

Gov. Rick Snyder received a more subdued welcome than other speakers at Flint Assembly but thanked workers for their efforts and told them the announcement "means growth will be here for many years to come."

U.S. Sen. Debbie Stabenow, D-Lansing, said the investment shows the importance of the federal bailout of GM.

"We are not going to have a middle class unless we make things in America," Stabenow said. "I'm very proud. I wouldn't have missed this for anything."

U.S. Rep. Dan Kildee, D-Flint, said workers earned the GM investment by building "the greatest products on the planet."

"You proved here in Michigan we don't turn our backs on our labor union heritage," Kildee said. "It is the strength of the American auto worker and the UAW ... that's paying off for the rest of the middle class of America."

Flint Assembly workers built 154,268 trucks here in 2012.

About 2,900 employees work in three shifts at the Van Slyke Road plant, a massive, 3.7-million-square-foot complex that opened in 1947.

GM also invested $328 million in the plant in 2011 to bring in equipment for producing the company's next generation truck and $21 million to relocate light-duty truck work here from Mexico in 2009.